Elevated titers of anti-GM1 ganglioside antibodies (anti-GM1)are associated with multifocal motor neuropathy, lower motor neuron disease syndromes, and with the acute motor axonal neuropathy variant of the Guillian-Barré syndrome.1-5 Assays for anti-GM1 antibodies are routinely used in clinical practice to aid in the evaluation of patients suspected of having these syndromes.
Anti-GM1 antibodies are typically measured using the ELISA system, in which increasing serum dilutions are tested for binding to GM1-coated microwells.6 However, the assay takes several days to perform, is costly, and is done at non-physiologic conditions of temperature and antibody concentration. Issues of methodology have also limited the usefulness of the technique.7-10 There is a need for a faster and more reliable test to detect and measure anti-GM1 antibodies.
Here we disclose a novel method for the rapid detection and quantitation of serum antibodies in serum. In the invention disclosed here we present data showing quantitation of serum anti-ganglioside antibodies in serum. The system utilizes a surface plasmon resonance-based optical biosensor. Gangliosides are immobilized on the surface of a sensor chip comprised of a carboxymethyl dextran layer linked to a thin gold film coated on a glass slide. The sensor chip is brought in contact with a flow cell carrying the analyte. Applying the phenomenon of surface plasmon resonance, possible interactions between the analyte in the flow cell and the gangliosides, leading to changes in the refractive index at the surface of the chip, can be followed.11,12 The binding of anti-GM1 antibodies in a sample to immobilized GM1 can be observed in real time without the use of secondary labels. The invention disclosed here reveals a method of diagnosing human diseases by detection and quantitation of antibodies in human sera.